The maximum value for the starting friction torque stated in the table is taken from the AFBMA standard for instrument ball bearings.
Applicable Conditions
- Ball bearings in ABEC 7P quality (with or without shields)
- Stainless steel (e.g. AISI 440C) and chrome steel (AISI 52100) materials
- Two-piece cage design
- Lubricated with instrument oil
These values are maximum values for myonic ball bearings of the relevant category. The definitions and test conditions are specified in the AFBMA standard.
Starting Friction Torque Specifications
| Bore diameter d (inch) | Outer diameter D (inch) | Test load (N) | Maximum starting frictional torque (μN·m) | ||
|---|---|---|---|---|---|
| Press fit | Normal fit | Loose fit | |||
| .0001"-.0003" (2-8 μm) | .0002"-.0005" (5-12 μm) | .0005"-.0008" (12-20 μm) | |||
| .0400 | .1250 | 0.75 | 18 | 15 | 14 |
| .0469 | .1563 | 0.75 | 18 | 15 | 14 |
| .0550 | .1875 | 0.75 | 18 | 15 | 14 |
| .0781 | .2500 | 0.75 | 18 | 15 | 14 |
| .0938 | .3125 | 0.75 | 18 | 15 | 14 |
| .1250 | .2500 | 0.75 | 18 | 15 | 14 |
| .1250 | .3125 | 0.75 | 18 | 15 | 14 |
| .1250 | .3750 | 0.75 | 20 | 15 | 15 |
| .1250 | .3750 | 4 | 50 | 45 | 42 |
| .1250 | .5000 | 4 | 50 | 45 | 42 |
| .1563 | .3125 | 0.75 | 18 | 15 | 14 |
| .1875 | .3125 | 0.75 | 18 | 15 | 14 |
| .1875 | .3750 | 0.75 | 20 | 16 | 15 |
| .1875 | .5000 | 4 | 65 | 55 | 50 |
| .2500 | .3750 | 0.75 | 18 | 15 | 14 |
| .2500 | .5000 | 4 | 60 | 52 | 48 |
| .2500 | .6250 | 4 | 70 | 60 | 55 |
| .2500 | .7500 | 4 | 80 | 70 | 65 |
| .3750 | .8750 | 4 | 110 | 95 | 90 |